1. Field of the Invention
The present invention relates to a hydraulic hammer operated by hydraulic pressure, and more particularly, to a hydraulic hammer having an improved seal ring contacting a piston thereof.
2. Description of the Related Art
In general, a hydraulic hammer mounted on an apparatus such as an excavator or a loader having a hydraulic pump, raises and lowers a piston installed inside the hammer by controlling high pressure fluid supplied by a hydraulic pump through a predetermined passage and valve to cause a hammer action, which crushes boulders or concrete by its force. The hydraulic hammer is categorized into a high pressure type, a low pressure type and a gas pressure type depending on the method of raising and lowering the piston.
FIG. 1 shows a prior low pressure type hydraulic hammer and FIG. 2 is an enlarged section view of the portion A of FIG. 1. The hydraulic hammer includes an accumulator 10, a valve housing 20, a seal housing 30, a cylinder 40 and a front head 50. A spool 21 is installed in the valve housing 20, a piston 60 is installed in the cylinder 40 and a tool 51 is installed in the front head 50.
Referring to FIG. 2, first and second grooves 41 and 42 and a hydraulic groove 43 are formed on an inner surface of a lower portion of the cylinder 40. Here, a wiper 61 is inserted into the first groove 41, one seal ring 62 is installed in the second groove 41, and a passage 63 for passing a pressurized fluid is connected to the hydraulic groove 43. A seal ring 62 is formed of a non-metal, so that a piston 60 and a cylinder 40 which are formed of a metal can stably move up and down without contacting with each other, and the fluid passing between the cylinder 40 and the piston 60 is prevented from leaking outward. The wiper 61 prevents an external foreign material from entering between the piston 60 and the cylinder 40.
The length of use of the seal ring 62 is typically 6 months. After about 6 months, the piston 60 becomes scratched, and the seal ring 62 wears rapidly, thereby requiring replacement of the seal ring 62. In order to replace the seal ring, the hydraulic hammer must be taken apart into numerous pieces.